In-mold labeling method

ABSTRACT

A shuttle-type blow molding machine and in-mold labeling apparatus for placing labels within open mold halves during movement of the mold halves from the blow station to the extrusion station.

This is a division of co-pending application Ser. No. 850,581 filed onApr. 11, 1986 and now U.S. Pat. No. 4,737,098.

The invention relates to blow molding of plastic containers withintegrally bonded labels and particularly to an improved in-moldlabeling machine and method for placing labels in the recesses of openmold halves during movement of the mold halves toward an extrusionstation.

In conventional blow molding machines, open mold halves are moved towarda parison at the extrusion station and closed to capture the parisonwithin the cavity between the mold halves. The closed mold then movesaway from the extrusion station to a blow mold station where thecaptured molten parison is blow molded to expand against the cavity andform the desired container. Following opening of the mold halves andejection of the blow molded container, the open mold halves are movedback to the extrusion station to capture another length of parison andinitiate a new cycle of operation. Blow molding machines are providedwith in-mold labeling apparatus operable to pick up labels from labelmagazines and transfer these labels to the mold recesses of stationaryopen mold halves before the mold halves close to capture the parison.

The length of the conventional cycle of operation for blow moldinglabeled containers is greater than the cycle of operation for blowmolding containers without labels, thereby decreasing the rate at whicha given machine can manufacture labeled containers below the rate atwhich the same machine can manufacture unlabeled containers. Forinstance, in a shuttle-type blow molding machine the length of theinterval during which the mold halves are held stationary to receivelabels may amount to as much as 5 to 10 percent of the total cycle time.Eliminating this pause would increase the efficiency of the machine.

The disclosed in-mold labeling machine is used to place labels in themold halves without increasing the cycle time over that formanufacturing unlabeled containers. The machine includes a labeltransfer assembly having a pair of label transfer heads movable betweena retracted position at label magazines located away from the extrusionstation and an extended position between the open mold halves as theymove toward the extrusion station. The mold halves are mounted on a moldtransfer carriage which moves between the blow mold and extrusionstations. A bracket on this carriage extends toward the label transfercarriage and carries a registry plate. This plate engages the extendedlabel transfer carriage to assure that the labels on the label transferheads between the open mold halves are in proper registry with thecavities in the moving open mold halves. During the continued movementof the open mold halves toward the extrusion station registry ismaintained, the two carriages move together and the label transfer headsare moved apart to accurately seat the labels within the mold halves.

As the label transfer assembly is pushed by the blow mold assembly,contact between the assemblies and resultant registry between the labeltransfer heads and the mold recesses is maintained by a force whichresists movement of the label transfer assembly and biases the assemblyagainst the plate.

The labels are preferably transferred to the open mold halves before themold assembly reaches the mold extrusion station. Following the transferto the mold halves, the label transfer heads are withdrawn from the moldrecesses and the label transfer assembly is rapidly moved away from themoving blow mold assembly to assure that the label transfer heads arewithdrawn from between the mold halves before the mold halves close onthe parison at the extrusion station. In this way, the labels areautomatically placed within the recesses of the mold halves during thenormal cycle of operation of the blow molding machine.

Other objects and features of the invention will become apparent as thedescription proceeds, especially when taken in conjunction with theaccompanying drawings illustrating the invention, of which there are 3sheets and one embodiment.

IN THE DRAWINGS

FIGS. 1 and 2 are top and side views respectively of a blow moldingmachine and in-mold labeling apparatus according to the invention;

FIG. 3 is a sectional view taken along line 3--3 of FIG. 1;

FIGS. 4 through 8 are representational views illustrating the cycle ofoperation of the machine; and

FIG. 9 is a view illustrating a portion of the hydraulic controlcircuitry of the machine.

Shuttle-type blow molding machine 10 includes a frame 12, a blow moldingassembly 14 mounted on the frame and a label transfer assembly 16 alsomounted on the frame immediately to one side of the blow moldingassembly 14. Parts of the frame are omitted from the drawings.

The blow molding assembly 14 includes a mold transfer carriage 18 with apair of blow mold halves 20 and 22. Each mold half is provided with arecess 24 such that when the halves are closed the recesses define ablow mold cavity. A vacuum manifold (not illustrated) in each mold half20, 22 opens at a plurality of holes formed on the bottoms of therecesses 24 for holding labels within the recesses prior to and duringblow molding. The manifolds are connected to a vacuum source throughoutoperation of machine 10.

The mold halves are mounted on platens 26 which are in turn secured tothe ends of slide rods 28. These rods extend through slide bushings 30on fixed support plates 32. The blow molding assembly includes a drive(not illustrated) for selectively moving the mold halves between openand closed positions as indicated in solid and dotted lines respectivelyin FIG. 1.

The mold transfer carriage is mounted on a pair of spaced parallel sliderods 34 permanently secured to frame 12. As shown in FIG. 2, piston rod36 of fluid cylinder 38 is secured to the carriage 18. The cylinder ismounted on frame 12 so that extension of the fluid cylinder positionsthe mold transfer assembly at blow mold station 40 as shown in FIG. 2and retraction of the cylinder 38 moves the carriage 18 along the rodsto the extrusion station 42. A parison extrusion head 44 is locatedabove the mold halves when at the extrusion station and a blow head 46is located above the mold halves when at the blow molding station. Sliderods 34 extend downwardly at a shallow angle from the extrusion stationto the blow mold station so that movement of the assembly along the rodsshifts the mold halves both downwardly and laterally away from theextrusion head 44.

Label transfer assembly 16 is located on the side of adjacent extrusionstation 42 away from the blow mold station 40. Assembly base plate 48 ismounted on frame 12. A pair of spaced, parallel slide rods 50 aremounted on plate 48 in end blocks 52 with the rods 50 extending in adirection toward the extrusion station parallel to rods 34. Labeltransfer carriage 54 shown in FIGS. 1 and 2 includes a support plate 56above plate 48, a pair of like slide bodies 58 and 60 and a top plate 62spaced above plate 56. The top plate is joined to the base plate bysupport 64.

The label transfer carriage 54 is mounted on rods 50 by means of slidebushings 66 mounted on the lower surface of plate 56. Fluid cylinder 68is mounted on an extension of plate 48 and includes a piston rod (notillustrated) attached to a bracket on the bottom of plate 56 so thatretraction and extension of the cylinder 68 moves the label transfercarriage 54 along rods 50 toward and away from the adjacent extrusionstation 42 of blow molding assembly 14.

A pair of spaced parallel slide rods 70 are mounted on the top of plate56 in end blocks 72. These rods extend perpendicularly to slide rods 50.Rods 70 are located beneath the top plate 62. The slide bodies 58 and 60carry bushings on rods 70 permitting movement of the slide bodies alongthe rods. The carriage 54 includes a drive connection 73 on plate 62joining the two slide bodies 58 and 60. The drive connection may be adouble ended arm rotatably mounted on plate 62 with the ends of the armshaving slide connections with the slide bodies such that rotation of thearm moves the slide bodies back and forth in opposite directions alongthe rods 70 between open and closed positions. The piston rod of fluidcylinder 74 mounted on plate 56 is connected to slide body 60 such thatextension of the cylinder moves both slide bodies toward each other to aclosed position and retraction of the air cylinder moves both bodies toan open position. The movement of body 60 is communicated to body 58 inthe opposite direction by the connection 73. The opened and closedpositions of the slide bodies are determined by appropriate stopslimiting movement of the slide bodies on rods 70.

Like elongate label transfer arms 76, 78 extend from the label transfercarriage 54 toward the extrusion station 42. Arm 76 is bolted to the topof the slide body 58 and arm 78 is similarly bolted to the top of slidebody 60. The arms 76 and 78 extend directly toward the blow moldingmachine, parallel to the axies of slide rods 34 and 50.

A vacuum label transfer head 80 faces outwardly from the free end ofeach arm 76 and 78. The transfer heads 80 include vacuum cups joined toa vacuum source through suitable vacuum lines and a control valve asmore fully pointed out during the description of the operation ofmachine 10. The heads are formed of plastic to reduce injury to the moldhalves in the event the mold halves should accidentally close on theheads.

A pair of like conventional label magazines 82 are mounted on frame 12between the label transfer carriage and the extrusion station of theassembly 14. Magazines 82 maintain individual labels 84 at pickuplocations 86 located equal distances to either side of the arms 76 and78 and spaced apart from each other the same distance as the bottoms ofthe blow mold recesses 24 are spaced apart when the mold halves areopen. See FIG. 1.

It is contemplated that different types of molds may be used in formingcontainers using in-mold label machine 10 and, in some cases, the depthsof the mold recesses which receive the labels may vary. In order toaccommodate molds of different depths, the label magazines 82 areadjustably mounted on frame 12 to assure that the label pickup locations86 are spaced apart a distance equal to the distance between the bottomsof the mold recesses when the mold halves are open. The open or maximumspacing between the slide bodies 58 and 60 is likewise adjustable toaccommodate different depth mold halves and to assure that the slidebodies and label transfer heads 80 move apart a distance sufficient topick up labels at locations 86 and deposit the labels in the moldrecesses.

The mold transfer carriage 18 includes a support arm 88 extendingbetween and joining plates 32. The arm 88 is located below the sliderods 34 supporting the carriage. As indicated in FIG. 2, the piston rod36 of cylinder 38 is joined to arm 88.

The mold transfer carriage also includes a generally vee-shaped bracket90, with the legs of the bracket mounted on the tops of the two plates32. The bracket legs are formed from a metal plate and each include aportion 92 extending inwardly from the plate toward the other leg and astraight portion 94 extending toward the label transfer assembly 16. Asindicated in FIG. 2, the bracket legs are mounted on the horizontal topsof plates 32. Angle spacers 95 are provided so that the legs extend fromthe plates parallel to the axes of slide rods 34 and 50.

The ends of the bracket arms away from plate 32 are joined to a U-shapedregistry plate 96 shown in FIG. 3. Plate 96 extends perpendicularly tothe bracket arms and to the axies of rods 34 and 50. Gusset plates 98support the alignment plate on the bracket arms. As shown in FIG. 3, thecontact portion 100 of plate 96 is located below leg portions 94 withthe label transfer arms 76 and 78 extending through the recess 102 inplate 96 and below the bracket legs. The label transfer assembly 16carries a pair of contact rollers or stops 104 facing registry plate 96and engagable with the plate contact portion 100 during movement of themold transfer carriage from the blow mold station 40 toward theextrusion station 42 as shown in FIGS. 1 through 3.

The operation of machine 10 will now be described. During operation acontinuous parison 106 is extruded from head 44, the mold transfercarriage is moved back and forth between stations 40 and 42, the moldhalves open and close, capture the parison, and transfer the parison tostation 40 where the parison is expanded to form a blow moldedcontainer. The labels form integral parts of the blow molded container.

During return movement of the carriage to station 42, the label transferassembly automatically and accurately places a pair of labels 84 at thebottoms of the mold recesses 24 so that the labels are in place when thecarriage returns to the station and the mold halves close and capturethe parison. The labels are placed in the mold halves without any pauseor dwell time in the cycle of the blow molding assembly.

In FIG. 4 cylinder 38 is extended to position the mold transfer assembly18 at blow mold station 40 and the molds 20 and 22 are closed about acaptured portion of parison 106. In this position the label transferassembly cylinder is extended so that carriage 54 is retracted to theright along slide rods 50. Cylinder 74 is retracted so that the slidebodies are apart and the label transfer heads are against the labels inmagazines 120 at label pick-up positions 86. Vacuum is supplied to theheads to capture the presented labels.

When fluid cylinder 38 is fully extended with carriage 18 at station 40the blow head 46 is lowered to engage the exposed upper end of thecaptured parison and compressed air is flowed through the head to expandthe parison in the mold cavity and form a container having a shapedefined by the shape of the cavity. During blow molding of the parison,the labels are bonded to the sides of the resultant container. Followingblow molding head 46 is retracted and the mold halves are opened, thecompleted container is ejected from between the mold halves and cylinder38 is retracted to return the carriage 18 toward the extrusion station42.

During blow molding, the transfer heads 80 engage the labels inpositions 86 during a timing cycle initiated upon movement of the labelheads against the labels to assure that the heads capture the labels.Upon this expiration of interval, the cylinder 74 is extended to movethe slide bodies 58 and 60, arms 76 and 78 and heads 80 with attachedlabels from the open to the closed position as shown in FIG. 5. In theclosed position, the arms are spaced apart a distance to either side ofthe parison 106 sufficient to permit movement of the label transfercarriage toward the mold assembly 14 free of the parison as indicated inFIG. 1.

After the label transfer heads have been moved to the retractedposition, cylinder 68 is retracted to move label transfer carriage,arms, heads and labels toward the blow molding assembly 14 to the fullyextended position as shown in FIG. 6 with the label arms extending pastthe parison 106 and the labels adjacent the closed mold halves at theblow mold station. In this position, cylinder 68 holds the labeltransfer carriage 54 against a stop.

Upon completion of the blow molding, opening of the mold halves andejection of the completed container as shown in FIG. 6, cylinder 38 isretracted to move the open mold halves from the blow mold station towardthe extrusion station. As the blow mold carriage moves back along rods34 toward the extrusion station plate 96 moves toward the label transfercarriage 54 and engages rollers or stops 104 to move the carriage backin the same direction along rods 50. Opposite movement of the labeltransfer carriage increases the pressure of the hydraulic fluid incircuitry for cylinder 68 as shown in FIG. 9. Before contact betweenplate 96 and stops 104, high pressure fluid is supplied through controlvalve 108 and line 110 to the side of the cylinder 68 forcing thecylinder toward the retracted position and biasing the label transfercarriage 54 toward the extended position of FIG. 6. Cylinder line 112 isconnected to a low pressure return line by valve 108. A pressure reliefvalve 114 is connected between lines 110 and 112 and relieves fluid inline 110 to line 112 when the pressure in line 110 exceeds a setpressure above the normal operating pressure.

The registry plate 96 contacts stop 104 and the mold transfer carriage18 picks up label transfer carriage 54 and moves the carriage with itduring the return of the extrusion station 42. The force exerted on themold transfer carriage by relatively large diameter cylinder 38 isgreater than the opposing force exerted on the label transfer carriageby the relatively smaller diameter cylinder 68. Cylinder 68 continues tobias the label transfer assembly against plate 96 thereby maintainingproper registry between the two assemblies during the return stroke ofthe mold transfer carriage. Initial movement of the label transfercarriage with the mold transfer carriage increases the pressure in line110 above the set pressure of relief valve 114 to permit the hydraulicfluid displaced by extension of cylinder 68 to flow to low pressure line112. Valve 108 is not shifted during the return stroke of the labeltransfer assembly. In this way, the cylinder 68 continues to bias thelabel transfer assembly against the alignment plate 96 during the returnstroke.

The label transfer heads 80 are located a distance from stops 104 sothat when the stops are held against plate 96 the transfer heads are inalignment with the mold recesses 24 of open mold halves 20 and 22. Thebiasing force provided by cylinder 68 during return movement of the moldand label transfer carriages maintains alignment of the heads with thecavities.

Immediately following registry between the label transfer carriage andmoving mold transfer carriage the cylinder 74 is retracted to move thelabel transfer heads apart and seat the labels in the mold recesses 24of the mold halves 20 and 22 during movement back toward the extrusionstation 42. See FIG. 7.

The label transfer heads are maintained in the open position with thelabels held against the recesses 24 for a timing cycle sufficient toassure that the labels are picked up and held against the mold halvesvacuum manifolds. At the expiration of the timing cycle the vacuum isremoved from the transfer heads and cylinder 74 is extended to withdrawthe heads from the recesses. When the heads are fully retracted, valve108 is reversed and cylinder 68 moves the label transfer carriage 54 tothe right as shown in FIGS. 1 and 2 at a rate faster than the rate ofmovement of the mold transfer carriage so that the arms 76 and 78 andhead 80 are withdrawn from between the mold halves before the moldhalves reach the extrusion station 42.

FIG. 8 illustrates the position of the label and mold carriages when thelabel carriage with open mold halves has been returned to the extrusionstation. At this time, the normal cycle of operation of blow moldingassembly 14 recommences and the molds close to capture the parison,cylinder 38 is extended to move the mold assembly back to the blowstation 40, the captured parison is severed from the extrusion head 44and cylinder 74 is again retracted to move the label transfer headagainst the labels held in the pick up positions 86. Vacuum isreconnected to the heads to permit capture of the labels and the cycleof operation is finished.

In the cycle of operation, the labels are accurately and reliablypositioned in the mold halves during movement of the mold transfercarriage from the mold station to the extrusion station withoutlengthening the normal operating cycle of the machine. The cycle timefor manufacture of a labeled blow-molded bottle is decreased over thatof conventional blow molding machines where movement of the molds isstopped for an interval during which labels are placed in the moldcavities.

The label transfer assembly 16 is described in connection with ashuttle-type blow molding machine 10 where the blow mold assembly movesback and forth along a straight path between the extrusion and blowmolding stations. It is contemplated that a label transfer assembly maybe used in other types of blow molding machines to place labels in moldhalves as they move through a normal cycle of operation. For instance, alabel transfer assembly may be used to place labels in moving moldhalves where the mold halves are returned to the parison station alongeither straight or curved paths. Also, the label transfer assembly maybe used on rotary type blow molding machines where blow mold assembliesare continuously rotated past a number of stations and are not shuttledback and forth in opposite directions along a single path. It is alsocontemplated that the invention may be used to place a single label in amold cavity and to place one or more labels simultaneously in aplurality of mold cavities in case the blow molding machinesimultaneously blow molds a plurality of containers.

While we have illustrated and described a preferred embodiment of ourinvention, it is understood that this is capable of modification, and wetherefore do not wish to be limited to the precise details set forth,but desire to avail ourselves of such changes and alterations as fallwithin the purview of the following claims.

What we claim as our invention is:
 1. In a blow molding and labelingmachine of the type having a frame; a parison extrusion head forextruding a continuous parison down into an extrusion station; a blowhead at a blow molding station separated from the extrusion station,said head supplying air to expand the parison at the blow moldingstation and form a bottle; a mold transfer carriage including a pair ofblow mold halves, each blow mold half including a recess, the recessesdefining a blow mold cavity when the mold halves are closed; a fixedlabel magazine on the frame; and a label transfer assembly including avacuum label transfer head connected to a label transfer carriage; themethod of making plastic bottles with labels permanently bonded to thesides of the bottles comprising the steps of:A. moving the labeltransfer head repeatedly between the extrusion station and the blow moldstation with the mold halves open during movement from the blow moldstation to the extrusion station and with the mold halves closed duringmovement from the extrusion station to the blow mold station; B.positioning the label transfer head at the magazine, picking up a labelfrom the magazine on the head, and then moving the label transfer headand carried label to a position between the open mold halves as theymove from the blow mold station to the extrusion station with the labeltransfer head located immediately adjacent one moving open mold half; C.placing the label carried by the label transfer head in the recess inthe adjacent moving mold half without interrupting movement of the moldhalves to the extrusion station byi. forming a temporary physicalconnection between the mold half and the label transfer carriage so thatthe label transfer head and carried label move together with the moldhalf with the label facing but spaced away from the bottom of therecess, ii. maintaining the temporary physical connection and moving thelabel transfer head into the recess to seat the label against the bottomof the recess in physical contact with the mold half, iii. establishinga physical connection between the label and the bottom of the recess andthen breaking the connection between the label transfer head and label,iv. withdrawing the label transfer head from the recess and breaking thetemporary physical connection between the mold half and the labeltransfer carriage, and v. withdrawing the label transfer head frombetween the moving mold halves; D. closing the mold halves around theparison at the extrusion station to capture the parison in the labelledmold cavity; E. blowing the captured parison at the blow mold station toexpand the parison against the cavity and thereby form a labelled bottlein the cavity; and F. opening the mold halves and removing the labelledbottle.
 2. The method of claim 1 including the step of placing a secondlabel in the recess of the other moving mold half at the same time thelabel is placed in the recess of said one moving open mold half.
 3. Themethod of claim 1 including the step of moving the label transfer headback and forth along a single path extending between the extrusionstation and the blow mold station.